Process for making turbine or compressor blades



Oct. 3, 1961 w. s. HOLLIS ET AL 3,002,264

} PROCESS FOR MAKING TURBINE OR COMPRESSOR BLADES Filed May 25, 1955 4 sheets-sheet 1 Attorn' ey;

Oct. 3, 1961 w. s. HOLLIS ET AL 3,002,264

PROCESS FOR MAKING TURBINE OR COMPRESSOR BLADES Filed May 25, 1955 4 Sheets-Sheet 2 I nve tors xiiijmm L4.

.4 d gAttorneyr Oct. 3, 1961 w. s. HOLLIS ET AL 3,

PROCESS FOR MAKING TURBINE 0R COMPRESSOR BLADES I Filed May 25, 1955 4 Sheets-Sheet 5 Fig-3 MMJzil/L65 Oct. 3, 1961 w. s. HOLLIS ET AL PROCESS FOR MAKING TURBINE OR COMPRESSOR BLADES 4 Sheets-Sheet 4 Filed May 25, 1955 3,002,264 PROCESS FOR MAKING TURBINE OR COMPRESSOR BLADES William Stephen Hollis, Banstead, and John Owen Mayer,

West Drayton, England, assignors to Power Jets (Research and Development) Limited, London, England, a British company Filed May 25, 1955, Ser. No. 511,083 3 Claims. (Cl. 29156.8)

This application is a continuation-in-part of our patent application Serial No. 433,762, now abandoned.

The invention relates to a process of making blades suitable for use in a bladed turbine of an elastic fluid turbine plant or in a bladed compressor by rolling the blades from a metal blank. One such process is set forth in our Patent No. 2,972,181, granted February 21, 1961, and comprises rolling a series of blades with roots in a long strip, the essential feature of the process being that before the final rolling the strip of material is preformed to give it a series of enlargements each of which ultimately forms the root of a blade.

The process according to the present invention consists of forming a pair of blades suitable for use in a bladed turbine of an elastic fluid turbine plant or in a bladed compressor by passing a blank through blade-forming rolls and is characterised by the step of pre-forming the blank to give it an enlargement mid-way between the ends of the blank from which enlargement the root of each blade is formed.

The invention is further characterised by rolling the arm of the said blank to blade form longitudinally, on each side of the enlargement in succession, or transversely on both sides of the enlargement simultaneously.

' In the accompanying drawings:

FIG. 1 illustrates one method of upsetting a metal strip to form a blank with a central enlargement.

FIG. 2 shows a pair of rolls for longitudinally rolling the arms of the blank to blade form.

FIG. 3 illustrates the successive steps in the bladeforming process from the metal strip to the finished blade pair.

FIGS. 4 and 5 show in perspective two forms of rolls for transversely rolling the arms of the blank to blade form.

In one particular process according to the invention, as illustrated in part by FIG. 1, a metal strip 1' (as in FIG. 3a) of a length suitable for making two blades each having a root and which has, before it enters the device shown in FIG. 1, a cross-section chosen to suit rolling to the desired form, is upset in this device to form an enlargement 2 midway along its length from which two roots may be subsequently formed.

Alternatively the upset strip or blank may be obtained by dissecting a long strip at points mid-way between the adjacent enlargements, the strip having been upset in the device shown in FIG. 1. This device is the same as that set forth in our co-pending patent application Serial No. 366,998 but adjusted to form enlargements along the strip at intervals equal to the length of a blank from which two blades may be formed. The device enables a long strip or a continuity of short strips to be fed into the device through feed rolls at a substantially constant speed.

The blade blanks (as in FIG. 3b) are then passed individually through the indented rolls shown in FIG. 2, FIG. 4 or FIG. 5 to produce on each side of the enlargement the desired blade form 4.

As shown in FIG. 1 for forming the enlargements, two vices 5 and 6 which are spaced apart by a short distance grip the strip 1 without slipping, by means of vice blocks 7 and 8 closed by hydraulic actuators 9 and 10, and then approach each other to enlarge the strip between them States Patent G "ice while the strip is hot. Heating is done in well-known manner by passing electric current from the transformer 13 through leads 14 and 14a and so through the part of the strip 1 between the two vice-blocks, which latter serve as the current-feeding electrodes. The vice-blocks 7 and 8 are insulated from the rest of the vices 5 and 6 at 11 and 12. The mechanism for moving the vices allows current to pass for sufiicient time to heat the metal strip before the upsetting begins. High-frequency induction heating may alternatively be used. After upset-ting the strip, the vice-blocks 7 and 8 release their grip and are separated by the actuators 9 and 10; the vices move backward through the required pitch relatively to the feed before they again grip the strip (or grip the next short strip as the case may be) and repeat the operation for forming the next enlargement, and soon.

The process could involve step-by-step motion of the strip or strips between each upsetting operation. In order however to keep up continuous motion so that the strip or strips can move continuously through the device of FIG. 1, the vices are carried by platforms 15 and 16' which can move with the strip while the vices are gripping and which, after the vices release their grip, can move back to their initial positions ready for the vices to grip the strip again or the next short strip. Both platforms are slidably mounted on the guides 17 carried by the stationary structure 18 which also carries bearings 19 supporting crankshaft 20 which is driven through gearing 21 and carries short cranks 22 and long cranks 23. Each pair of cranks 22 is connected by a connecting-rod 24 to the platform 15, the pin 26 on each connecting rod 24 being in an elongated hole 15a in the forked part 15b of the platform. Similarly each pair of long cranks 23 is connected by a connecting-rod 25 to the platform 16, the pin 27 on rod 25 being in a slot 16a in'the forked part 16b of the platform; slot 16a is longer than elongated hole 15a. The difference between the throw of cranks 22 and cranks 23, is equal to the difierence in travel between the vices as they separate.

When the cranks are at to the position shown, the vices will have come together; to leave space in which the upset can be formed-the vice-blocks must be set back, either wholly or by being recessed as shown in vice-block 8 at 811, which is the entry to the cavity 8a between the pair of blocks. The adjacent entry to the cavity in viceblock 7 may be similar. The blocks 8 are flared at the entry to 8a to provide for an initial curvature to be impressed on the strip where eventually the blade will merge into its root portion. The blocks may be further shaped at the entry to cavity 8a to form the enlargement with a central reduced portion or neck.

The strip 1 to which the process is to be applied is assumed to be of the said cross-section chosen to suit the ultimately desired blade section. As the strip material will usually be initially of some symmetrical section considerably different from the final blade section, and in particular of circular section, the strip will be reduced to the said chosen cross-section by flattening rolling before upsetting. When blades tapering along their length are to be rolled, rotary swaging of the strip is also carried out and preferably before the flattening, to-produce a strip made up of a succession of portions tapering up from a minimum to maximum width or diameter, and then down to a minimum again.

The strip 1 thus or otherwise prepared is then threaded through the vices 5 and 6which are openby feed rolls 28, and when the cranks 22 and 23 are in position just past the dead centre position shown in FIG. 1, the two vices are closed. The vice blocks 7 and 8 grip the strip, completing the electrical circuit from the transformer 13, so that heating current flows through a short length of the strip. Both vices will then be travelling at the same speed as the feed. The short cranks 22 are of such length and are driven at such speed that over an intermediate angle of travel while the upsetting is being done the speed at which the platform 15 is driven by cranks 22 does not greatly change. Initial movement of the vices will take up some of the clearance of the pins 26 and 27 in slots 15a and 16a. As the speed of pin 27, driven by the long or anks 23, begins to exceed the speed of platform 15, the pin 27 moves along the slot 16a until it reaches the end of the slot and can drive the platform 16. During this time interval after closure of the vices, determined by the length of slot 16a, the moving strip is merely being heated. Now the platform 16 will move faster than platform 15, and the two vices moving closer together will upset the locally heated strip. Before the cranks reach the outer dead centre the vices are released, the vice block 7 being opened sufficiently topass the en largernent formed by the upsetting; the strip is thus left free, and the vices are left free to be returned to their initial positions by the next 180 of movement of the cranks.

In one process according to the invention, the blade blanks, removed from the upsetting device whilst hot or with further heating if necessary, are transferred individually to the indented rolls shown in FIG. 2. With the pressure between the upper roll 29 and lower roll 30 released, the blank is fed between the rolls into the position shown in FIG. 2 in which the enlargement 2 is in alignment with corresponding indentations 29a and 30a in the two rolls. These indentations serve to enfold and locate the enlargement although not necessarily to shape it. From the position shown, the rolls are rotated to drive the blank longitudinally firstly in one direction and then in the opposite direction through the rolls to impart a blade form to each arm of the blank in succession.

After the rolling of one blade of the pair, the pressure,

between the rolls may be temporarily reduced to the min imum necessary to provide only sufficient friction to carry the blank back to the mid-position in which the enlargement seats between the indentations 29a and 30a, the pressure then being re-app-lied as necessary for rolling the other blade. After the rolling of the second blade the rolled blank is discharged from the rolls which are then returned to position ready for insertion of the new blank.

In an alternative process according to the invention, the blade blanks removed from the upsetting device whilst hot or with further heating if necessary are transferred individually to the indented rolls 29, 30 shown diagrammatically in FIG. 4 or FIG. which are coupled through gearing 31. Each blank is fed into the rolls with its length extending along the length of the rolls. blades are formed by rolling the arms of the blank across their width from edge to edge between the blade indentations 2% and 30b of the two rolls and at the same time the enlargement is gripped between the indentations 29a and 30a; the indentations 29a and 36a may be shaped to roll the enlargement at least partly to final root form. FIG. 4 shows rolls having indentations for producing straight or slightly twisted blades whilst the indentations in the rolls shown in FIG. 5 are suitable for forming considerably twisted blades. Thus the roll 29 in FIG. 5 has blade indentations 2% which gradually change to upstanding portions 290 projecting into the corresponding indentation in the other roll 30.

Reversal of the rolls may be normally unnecessary and so blanks may be fed into the IIOllS in succession to provide a substantially continuous rolling process. The rolls may however be reversible if required.

Itwill be observed that in the above-described alternative process, the properties of the blade material will be improved in the longitudinal direction by the initial rolling or drawing processes which are normally used to prepare a metal strip from which the blanks are formed, and the transverse properties will be improved by rolling the blank across its width.

The

The blade-forming indentations 29b and 30b in both the longitudinal and transverse rolling processes are, of course, unsymmetrical but may be arranged either (i) to form the leading edges of the two blades along the same side of the blank, as shown in FIG. 30, with the upper surface of the blank bearing a convex form to one side of the enlargement and a concave form to the other side thereof, or (ii) to form the convex surface of each blade on the upper surface of the blank, as shown in FIG. 3d, with each edge of the blank shaped to form a blade lead ing edge to one side of the enlargement and a trailing edge to the other side thereof.

To produce twisted blades, the blank may be rolled as for straight blades for example by the rolls of FIG. 4 and the twist subsequently imparted by a separate operation or alternatively the twist may be imparted during the rolling by appropriately formed indentations as shown in FIGS. 2 and 5. To facilitate such rolling of a twisted blade shrouds 31 in FIG. 2 are provided on one roll overlapping the other roll on each side.

The two blades thus rolled are parted in the middle of the root portion, giving two identical blades with roots. Any further operations that are necessary to complete the blade portion or the root or both are then performed on the individual blades. A pair of finished blades is shown in FIG. 3e with the original blade-root blank shown in dotted line. Although fir tree roots are here shown, the invention is particularly applicable to a bulb or other form of root or to a foot for holding on a rotor or stator without necessarily fitting in a seating. Some of these root forms may be obtained by suitably shaping the cavities 29a and 30a.

The invention is further applicable to the rolling of a blade core which is fluted to provide cooling passages and around which the aerofoil blade surface is subsequently placed.

We claim:

1. A process for forming a pair of compressor or turbine blades which comprises forming a blank by gripping with clamps at spaced points a strip of metal of crosssection suitable for rolling to blade section, electrically heating said strip between said clamps, and moving said clamps relative to each other to shorten the distance therebetween to form between the ends of the strip an enlargement of such a size that the roots of the pair of blades can be formed therefrom, rolling the arms of the blank on each side of the enlargement to blade section between blade forming rolls, and dividing the blank through the enlargement.

2. A process for forming a pair of compressor or turbine blades which comprises forming a blank by upsetting a strip of metal of cross-section suitable for rolling to blade section to form between the ends of the strip an enlargement of such size that the roots of the pair of blades can be formed therefrom, rolling the arms of the blank on each side of the enlargement to blade section between blade-forming rolls, each arm of the blank being rolled in a direction away from the enlargement, and

dividing the blank through the enlargement.

3. A process for forming a pair of compressor or turbine blades which comprises forming a blank by upsetting a strip of metal of cross-section suitable for rolling to blade section to form between the ends of the strip an enlargement of such size that the roots of the pair of blades can be formed therefrom, rolling the arms of the blank on each side of the enlargement to blade section between blade-forming rolls, the arms of the blank being rolled from edge to edge across their width, and dividing the blank through the enlargement.

References Cited in the file of this patent UNITED STATES PATENTS 1,448,371 Baehr Mar. 13, 1923 (Other references on following page) 5 UNITED STATES PATENTS Wilcox. Nov. 1, 1932 Witherow Aug. 15, 1933 Bedford Sept. 3, 1935 Harper Jan. 10, 1939 Rendleman June 10, 1941 Stine Sept. 2, 1941 Hanna June 14, 1949 6 Gibian Dec. 11, 1951 Atkinson Dec. 1, 1953 Shields Feb. 2, 1954 FOREIGN PATENTS Switzerland Dec. 16, 1919 Great Britain Sept. 8, 1927,: Great Britain Mar. 17, 1930 France Mar. 17, 1954 

